1. Field of the Invention
The present invention relates generally to computer systems. More particularly, the present invention relates to a communication bus.
2. Related Art
Since the introduction of the Audio/Modem Riser (xe2x80x9cAMRxe2x80x9d) in recent years, the computer industry has been struggling to define a next generation communications riser card, which can offer extended functionality and yet maintain backward compatibility with the existing platforms, such as AMR. Riser cards are not intended to be sold as retail upgrade products. Instead, riser cards are available to Original Equipment Manufacturers (xe2x80x9cOEMxe2x80x9d) and system integrators as a resource to customize a system or a product line to the needs of market segments, market regions or individual users.
The AMR specification was introduced in 1998 as an open industry-standard that defines a hardware scalable OEM motherboard riser board and interface, which supports both audio and modem. AMR physically partitions and packages the analog I/O audio functions of modem circuitry together with a codec chip (which converts back and forth from analog to digital) on a small board that plugs directly into a computer""s motherboard. Having the circuitry on the board eliminates the need for obtaining agency certification for the manufacture of a new motherboard design, which is a lengthy process, instead, only the small board is certified. The small board is typically referred to as a riser because it rises above the motherboard rather than laying flatly on it.
Although AMR has provided the computer industry with some momentum and perspective, AMR has failed to remain responsive to today""s technological advancement and demands. In particular, AMR does not address the convergence and/or integration of various broadband, networking and advanced audio/modem technologies. For example, a riser could include several types of communication devices on the same small board, such as a digital subscriber line (xe2x80x9cDSLxe2x80x9d) device, a local area network (xe2x80x9cLANxe2x80x9d) device, a Home Phoneline Networking Alliance (xe2x80x9cHomePNAxe2x80x9d) device, and an audio/modem device. Each of these devices requires a controller and a bus to communicate with its controller on the computer""s motherboard. Each link provided by a bus between a device and its controller must comply with specific characteristics for the signal between the device and its controller. Such signal characteristics may include, for example, signal names, descriptions, electrical properties, pin numbers and the like. Accommodation of several controllers and types of busses on the computer""s motherboard has several disadvantages. For example, accommodation of several controllers and types of busses can cause replication of components which is expensive, wastes space on the computer""s motherboard, and inefficiently coordinates utilization of the various technologies.
Accordingly, there is an intense need in the art for efficient linking between various communications technologies and/or devices, such as broadband and networking functions, and the host computer. Moreover, there is a need in the art for an efficient bus between various communications technologies and/or devices and the host computer for a next generation communications riser card, which provides an ability to support various communications technologies and/or devices.
In accordance with the purpose of the present invention as broadly described herein, there is provided method and system for a bus in the next generation communications riser card that is capable of supporting multiple communications devices. The invention addresses the intense need in the art for efficient linking between various communications technologies and/or devices, such as broadband and networking functions, and the host computer. Moreover, the invention provides an efficient bus between various communications technologies and/or devices and the host computer for a next generation communications riser card, which provides an ability to support various communications technologies and/or devices.
In one aspect of the invention, a communications system includes at least two communications devices, a communications bus, and a controller for communicating data with each of the communications devices via the communications bus. For example, the communications system may be a riser card, including communications devices such as a DSL device and a HomePNA device. The communications bus can be an integrated packet bus, for example, and the controller can be an integrated packet bus controller for controlling communications from the computer with the DSL and HomePNA devices using the integrated packet bus.
In one aspect, the communications bus supports a communications protocol which includes a control slot and at least one data slot. Each of the control slots and data slots has at least two bits. Each bit of the control slot selects which of the bits of the data slot belongs to which of the communications devices. For example, in the case of two communications devices, a 16-bit control slot can be filled with the bit pattern xe2x80x9c0000111111111111xe2x80x9d which indicates that for the following 16-bit data slot, the first 4 bits belong to the first communications device, the DSL device for example, and the second 12 bits belong to the second communications device, the HomePNA device for example.